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+.file "acos.s"
+
+
+// Copyright (c) 2000 - 2003 Intel Corporation
+// All rights reserved.
+//
+// Contributed 2000 by the Intel Numerics Group, Intel Corporation
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// * The name of Intel Corporation may not be used to endorse or promote
+// products derived from this software without specific prior written
+// permission.
+
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Intel Corporation is the author of this code, and requests that all
+// problem reports or change requests be submitted to it directly at
+// http://www.intel.com/software/products/opensource/libraries/num.htm.
+
+// History
+//==============================================================
+// 02/02/00 Initial version
+// 08/17/00 New and much faster algorithm.
+// 08/30/00 Avoided bank conflicts on loads, shortened |x|=1 and x=0 paths,
+// fixed mfb split issue stalls.
+// 05/20/02 Cleaned up namespace and sf0 syntax
+// 08/02/02 New and much faster algorithm II
+// 02/06/03 Reordered header: .section, .global, .proc, .align
+
+// Description
+//=========================================
+// The acos function computes the principal value of the arc cosine of x.
+// acos(0) returns Pi/2, acos(1) returns 0, acos(-1) returns Pi.
+// A doman error occurs for arguments not in the range [-1,+1].
+//
+// The acos function returns the arc cosine in the range [0, Pi] radians.
+//
+// There are 8 paths:
+// 1. x = +/-0.0
+// Return acos(x) = Pi/2 + x
+//
+// 2. 0.0 < |x| < 0.625
+// Return acos(x) = Pi/2 - x - x^3 *PolA(x^2)
+// where PolA(x^2) = A3 + A5*x^2 + A7*x^4 +...+ A35*x^32
+//
+// 3. 0.625 <=|x| < 1.0
+// Return acos(x) = Pi/2 - asin(x) =
+// = Pi/2 - sign(x) * ( Pi/2 - sqrt(R) * PolB(R))
+// Where R = 1 - |x|,
+// PolB(R) = B0 + B1*R + B2*R^2 +...+B12*R^12
+//
+// sqrt(R) is approximated using the following sequence:
+// y0 = (1 + eps)/sqrt(R) - initial approximation by frsqrta,
+// |eps| < 2^(-8)
+// Then 3 iterations are used to refine the result:
+// H0 = 0.5*y0
+// S0 = R*y0
+//
+// d0 = 0.5 - H0*S0
+// H1 = H0 + d0*H0
+// S1 = S0 + d0*S0
+//
+// d1 = 0.5 - H1*S1
+// H2 = H1 + d0*H1
+// S2 = S1 + d0*S1
+//
+// d2 = 0.5 - H2*S2
+// S3 = S3 + d2*S3
+//
+// S3 approximates sqrt(R) with enough accuracy for this algorithm
+//
+// So, the result should be reconstracted as follows:
+// acos(x) = Pi/2 - sign(x) * (Pi/2 - S3*PolB(R))
+//
+// But for optimization purposes the reconstruction step is slightly
+// changed:
+// acos(x) = Cpi + sign(x)*PolB(R)*S2 - sign(x)*d2*S2*PolB(R)
+// where Cpi = 0 if x > 0 and Cpi = Pi if x < 0
+//
+// 4. |x| = 1.0
+// Return acos(1.0) = 0.0, acos(-1.0) = Pi
+//
+// 5. 1.0 < |x| <= +INF
+// A doman error occurs for arguments not in the range [-1,+1]
+//
+// 6. x = [S,Q]NaN
+// Return acos(x) = QNaN
+//
+// 7. x is denormal
+// Return acos(x) = Pi/2 - x,
+//
+// 8. x is unnormal
+// Normalize input in f8 and return to the very beginning of the function
+//
+// Registers used
+//==============================================================
+// Floating Point registers used:
+// f8, input, output
+// f6, f7, f9 -> f15, f32 -> f64
+
+// General registers used:
+// r3, r21 -> r31, r32 -> r38
+
+// Predicate registers used:
+// p0, p6 -> p14
+
+//
+// Assembly macros
+//=========================================
+// integer registers used
+// scratch
+rTblAddr = r3
+
+rPiBy2Ptr = r21
+rTmpPtr3 = r22
+rDenoBound = r23
+rOne = r24
+rAbsXBits = r25
+rHalf = r26
+r0625 = r27
+rSign = r28
+rXBits = r29
+rTmpPtr2 = r30
+rTmpPtr1 = r31
+
+// stacked
+GR_SAVE_PFS = r32
+GR_SAVE_B0 = r33
+GR_SAVE_GP = r34
+GR_Parameter_X = r35
+GR_Parameter_Y = r36
+GR_Parameter_RESULT = r37
+GR_Parameter_TAG = r38
+
+// floating point registers used
+FR_X = f10
+FR_Y = f1
+FR_RESULT = f8
+
+
+// scratch
+fXSqr = f6
+fXCube = f7
+fXQuadr = f9
+f1pX = f10
+f1mX = f11
+f1pXRcp = f12
+f1mXRcp = f13
+fH = f14
+fS = f15
+// stacked
+fA3 = f32
+fB1 = f32
+fA5 = f33
+fB2 = f33
+fA7 = f34
+fPiBy2 = f34
+fA9 = f35
+fA11 = f36
+fB10 = f35
+fB11 = f36
+fA13 = f37
+fA15 = f38
+fB4 = f37
+fB5 = f38
+fA17 = f39
+fA19 = f40
+fB6 = f39
+fB7 = f40
+fA21 = f41
+fA23 = f42
+fB3 = f41
+fB8 = f42
+fA25 = f43
+fA27 = f44
+fB9 = f43
+fB12 = f44
+fA29 = f45
+fA31 = f46
+fA33 = f47
+fA35 = f48
+fBaseP = f49
+fB0 = f50
+fSignedS = f51
+fD = f52
+fHalf = f53
+fR = f54
+fCloseTo1Pol = f55
+fSignX = f56
+fDenoBound = f57
+fNormX = f58
+fX8 = f59
+fRSqr = f60
+fRQuadr = f61
+fR8 = f62
+fX16 = f63
+fCpi = f64
+
+// Data tables
+//==============================================================
+RODATA
+.align 16
+LOCAL_OBJECT_START(acos_base_range_table)
+// Ai: Polynomial coefficients for the acos(x), |x| < .625000
+// Bi: Polynomial coefficients for the acos(x), |x| > .625000
+data8 0xBFDAAB56C01AE468 //A29
+data8 0x3FE1C470B76A5B2B //A31
+data8 0xBFDC5FF82A0C4205 //A33
+data8 0x3FC71FD88BFE93F0 //A35
+data8 0xB504F333F9DE6487, 0x00003FFF //B0
+data8 0xAAAAAAAAAAAAFC18, 0x00003FFC //A3
+data8 0x3F9F1C71BC4A7823 //A9
+data8 0x3F96E8BBAAB216B2 //A11
+data8 0x3F91C4CA1F9F8A98 //A13
+data8 0x3F8C9DDCEDEBE7A6 //A15
+data8 0x3F877784442B1516 //A17
+data8 0x3F859C0491802BA2 //A19
+data8 0x9999999998C88B8F, 0x00003FFB //A5
+data8 0x3F6BD7A9A660BF5E //A21
+data8 0x3F9FC1659340419D //A23
+data8 0xB6DB6DB798149BDF, 0x00003FFA //A7
+data8 0xBFB3EF18964D3ED3 //A25
+data8 0x3FCD285315542CF2 //A27
+data8 0xF15BEEEFF7D2966A, 0x00003FFB //B1
+data8 0x3EF0DDA376D10FB3 //B10
+data8 0xBEB83CAFE05EBAC9 //B11
+data8 0x3F65FFB67B513644 //B4
+data8 0x3F5032FBB86A4501 //B5
+data8 0x3F392162276C7CBA //B6
+data8 0x3F2435949FD98BDF //B7
+data8 0xD93923D7FA08341C, 0x00003FF9 //B2
+data8 0x3F802995B6D90BDB //B3
+data8 0x3F10DF86B341A63F //B8
+data8 0xC90FDAA22168C235, 0x00003FFF // Pi/2
+data8 0x3EFA3EBD6B0ECB9D //B9
+data8 0x3EDE18BA080E9098 //B12
+LOCAL_OBJECT_END(acos_base_range_table)
+
+.section .text
+GLOBAL_LIBM_ENTRY(acos)
+acos_unnormal_back:
+{ .mfi
+ getf.d rXBits = f8 // grab bits of input value
+ // set p12 = 1 if x is a NaN, denormal, or zero
+ fclass.m p12, p0 = f8, 0xcf
+ adds rSign = 1, r0
+}
+{ .mfi
+ addl rTblAddr = @ltoff(acos_base_range_table),gp
+ // 1 - x = 1 - |x| for positive x
+ fms.s1 f1mX = f1, f1, f8
+ addl rHalf = 0xFFFE, r0 // exponent of 1/2
+}
+;;
+{ .mfi
+ addl r0625 = 0x3FE4, r0 // high 16 bits of 0.625
+ // set p8 = 1 if x < 0
+ fcmp.lt.s1 p8, p9 = f8, f0
+ shl rSign = rSign, 63 // sign bit
+}
+{ .mfi
+ // point to the beginning of the table
+ ld8 rTblAddr = [rTblAddr]
+ // 1 + x = 1 - |x| for negative x
+ fma.s1 f1pX = f1, f1, f8
+ adds rOne = 0x3FF, r0
+}
+;;
+{ .mfi
+ andcm rAbsXBits = rXBits, rSign // bits of |x|
+ fmerge.s fSignX = f8, f1 // signum(x)
+ shl r0625 = r0625, 48 // bits of DP representation of 0.625
+}
+{ .mfb
+ setf.exp fHalf = rHalf // load A2 to FP reg
+ fma.s1 fXSqr = f8, f8, f0 // x^2
+ // branch on special path if x is a NaN, denormal, or zero
+(p12) br.cond.spnt acos_special
+}
+;;
+{ .mfi
+ adds rPiBy2Ptr = 272, rTblAddr
+ nop.f 0
+ shl rOne = rOne, 52 // bits of 1.0
+}
+{ .mfi
+ adds rTmpPtr1 = 16, rTblAddr
+ nop.f 0
+ // set p6 = 1 if |x| < 0.625
+ cmp.lt p6, p7 = rAbsXBits, r0625
+}
+;;
+{ .mfi
+ ldfpd fA29, fA31 = [rTblAddr] // A29, fA31
+ // 1 - x = 1 - |x| for positive x
+(p9) fms.s1 fR = f1, f1, f8
+ // point to coefficient of "near 1" polynomial
+(p7) adds rTmpPtr2 = 176, rTblAddr
+}
+{ .mfi
+ ldfpd fA33, fA35 = [rTmpPtr1], 16 // A33, fA35
+ // 1 + x = 1 - |x| for negative x
+(p8) fma.s1 fR = f1, f1, f8
+(p6) adds rTmpPtr2 = 48, rTblAddr
+}
+;;
+{ .mfi
+ ldfe fB0 = [rTmpPtr1], 16 // B0
+ nop.f 0
+ nop.i 0
+}
+{ .mib
+ adds rTmpPtr3 = 16, rTmpPtr2
+ // set p10 = 1 if |x| = 1.0
+ cmp.eq p10, p0 = rAbsXBits, rOne
+ // branch on special path for |x| = 1.0
+(p10) br.cond.spnt acos_abs_1
+}
+;;
+{ .mfi
+ ldfe fA3 = [rTmpPtr2], 48 // A3 or B1
+ nop.f 0
+ adds rTmpPtr1 = 64, rTmpPtr3
+}
+{ .mib
+ ldfpd fA9, fA11 = [rTmpPtr3], 16 // A9, A11 or B10, B11
+ // set p11 = 1 if |x| > 1.0
+ cmp.gt p11, p0 = rAbsXBits, rOne
+ // branch on special path for |x| > 1.0
+(p11) br.cond.spnt acos_abs_gt_1
+}
+;;
+{ .mfi
+ ldfpd fA17, fA19 = [rTmpPtr2], 16 // A17, A19 or B6, B7
+ // initial approximation of 1 / sqrt(1 - x)
+ frsqrta.s1 f1mXRcp, p0 = f1mX
+ nop.i 0
+}
+{ .mfi
+ ldfpd fA13, fA15 = [rTmpPtr3] // A13, A15 or B4, B5
+ fma.s1 fXCube = fXSqr, f8, f0 // x^3
+ nop.i 0
+}
+;;
+{ .mfi
+ ldfe fA5 = [rTmpPtr2], 48 // A5 or B2
+ // initial approximation of 1 / sqrt(1 + x)
+ frsqrta.s1 f1pXRcp, p0 = f1pX
+ nop.i 0
+}
+{ .mfi
+ ldfpd fA21, fA23 = [rTmpPtr1], 16 // A21, A23 or B3, B8
+ fma.s1 fXQuadr = fXSqr, fXSqr, f0 // x^4
+ nop.i 0
+}
+;;
+{ .mfi
+ ldfe fA7 = [rTmpPtr1] // A7 or Pi/2
+ fma.s1 fRSqr = fR, fR, f0 // R^2
+ nop.i 0
+}
+{ .mfb
+ ldfpd fA25, fA27 = [rTmpPtr2] // A25, A27 or B9, B12
+ nop.f 0
+(p6) br.cond.spnt acos_base_range;
+}
+;;
+
+{ .mfi
+ nop.m 0
+(p9) fma.s1 fH = fHalf, f1mXRcp, f0 // H0 for x > 0
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+(p9) fma.s1 fS = f1mX, f1mXRcp, f0 // S0 for x > 0
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+(p8) fma.s1 fH = fHalf, f1pXRcp, f0 // H0 for x < 0
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+(p8) fma.s1 fS = f1pX, f1pXRcp, f0 // S0 for x > 0
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fRQuadr = fRSqr, fRSqr, f0 // R^4
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fB11 = fB11, fR, fB10
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fB1 = fB1, fR, fB0
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fB5 = fB5, fR, fB4
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fB7 = fB7, fR, fB6
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fB3 = fB3, fR, fB2
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fnma.s1 fD = fH, fS, fHalf // d0 = 1/2 - H0*S0
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fR8 = fRQuadr, fRQuadr, f0 // R^4
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fB9 = fB9, fR, fB8
+ nop.i 0
+}
+;;
+{.mfi
+ nop.m 0
+ fma.s1 fB12 = fB12, fRSqr, fB11
+ nop.i 0
+}
+{.mfi
+ nop.m 0
+ fma.s1 fB7 = fB7, fRSqr, fB5
+ nop.i 0
+}
+;;
+{.mfi
+ nop.m 0
+ fma.s1 fB3 = fB3, fRSqr, fB1
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fH = fH, fD, fH // H1 = H0 + H0*d0
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fS = fS, fD, fS // S1 = S0 + S0*d0
+ nop.i 0
+}
+;;
+{.mfi
+ nop.m 0
+(p9) fma.s1 fCpi = f1, f0, f0 // Cpi = 0 if x > 0
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+(p8) fma.s1 fCpi = fPiBy2, f1, fPiBy2 // Cpi = Pi if x < 0
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fB12 = fB12, fRSqr, fB9
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fB7 = fB7, fRQuadr, fB3
+ nop.i 0
+}
+;;
+{.mfi
+ nop.m 0
+ fnma.s1 fD = fH, fS, fHalf // d1 = 1/2 - H1*S1
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fnma.s1 fSignedS = fSignX, fS, f0 // -signum(x)*S1
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fCloseTo1Pol = fB12, fR8, fB7
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fH = fH, fD, fH // H2 = H1 + H1*d1
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fS = fS, fD, fS // S2 = S1 + S1*d1
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ // -signum(x)* S2 = -signum(x)*(S1 + S1*d1)
+ fma.s1 fSignedS = fSignedS, fD, fSignedS
+ nop.i 0
+}
+;;
+{.mfi
+ nop.m 0
+ fnma.s1 fD = fH, fS, fHalf // d2 = 1/2 - H2*S2
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ // Cpi + signum(x)*PolB*S2
+ fnma.s1 fCpi = fSignedS, fCloseTo1Pol, fCpi
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ // signum(x)*PolB * S2
+ fnma.s1 fCloseTo1Pol = fSignedS, fCloseTo1Pol, f0
+ nop.i 0
+}
+;;
+{ .mfb
+ nop.m 0
+ // final result for 0.625 <= |x| < 1
+ fma.d.s0 f8 = fCloseTo1Pol, fD, fCpi
+ // exit here for 0.625 <= |x| < 1
+ br.ret.sptk b0
+}
+;;
+
+
+// here if |x| < 0.625
+.align 32
+acos_base_range:
+{ .mfi
+ ldfe fCpi = [rPiBy2Ptr] // Pi/2
+ fma.s1 fA33 = fA33, fXSqr, fA31
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA15 = fA15, fXSqr, fA13
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA29 = fA29, fXSqr, fA27
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA25 = fA25, fXSqr, fA23
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA21 = fA21, fXSqr, fA19
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA9 = fA9, fXSqr, fA7
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA5 = fA5, fXSqr, fA3
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA35 = fA35, fXQuadr, fA33
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA17 = fA17, fXQuadr, fA15
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fX8 = fXQuadr, fXQuadr, f0 // x^8
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA25 = fA25, fXQuadr, fA21
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA9 = fA9, fXQuadr, fA5
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fms.s1 fCpi = fCpi, f1, f8 // Pi/2 - x
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA35 = fA35, fXQuadr, fA29
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA17 = fA17, fXSqr, fA11
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fX16 = fX8, fX8, f0 // x^16
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fA35 = fA35, fX8, fA25
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fA17 = fA17, fX8, fA9
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+ fma.s1 fBaseP = fA35, fX16, fA17
+ nop.i 0
+}
+;;
+{ .mfb
+ nop.m 0
+ // final result for |x| < 0.625
+ fnma.d.s0 f8 = fBaseP, fXCube, fCpi
+ // exit here for |x| < 0.625 path
+ br.ret.sptk b0
+}
+;;
+
+// here if |x| = 1
+// acos(1) = 0
+// acos(-1) = Pi
+.align 32
+acos_abs_1:
+{ .mfi
+ ldfe fPiBy2 = [rPiBy2Ptr] // Pi/2
+ nop.f 0
+ nop.i 0
+}
+;;
+.pred.rel "mutex", p8, p9
+{ .mfi
+ nop.m 0
+ // result for x = 1.0
+(p9) fma.d.s0 f8 = f1, f0, f0 // 0.0
+ nop.i 0
+}
+{.mfb
+ nop.m 0
+ // result for x = -1.0
+(p8) fma.d.s0 f8 = fPiBy2, f1, fPiBy2 // Pi
+ // exit here for |x| = 1.0
+ br.ret.sptk b0
+}
+;;
+
+// here if x is a NaN, denormal, or zero
+.align 32
+acos_special:
+{ .mfi
+ // point to Pi/2
+ adds rPiBy2Ptr = 272, rTblAddr
+ // set p12 = 1 if x is a NaN
+ fclass.m p12, p0 = f8, 0xc3
+ nop.i 0
+}
+{ .mlx
+ nop.m 0
+ // smallest positive DP normalized number
+ movl rDenoBound = 0x0010000000000000
+}
+;;
+{ .mfi
+ ldfe fPiBy2 = [rPiBy2Ptr] // Pi/2
+ // set p13 = 1 if x = 0.0
+ fclass.m p13, p0 = f8, 0x07
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fnorm.s1 fNormX = f8
+ nop.i 0
+}
+;;
+{ .mfb
+ // load smallest normal to FP reg
+ setf.d fDenoBound = rDenoBound
+ // answer if x is a NaN
+(p12) fma.d.s0 f8 = f8,f1,f0
+ // exit here if x is a NaN
+(p12) br.ret.spnt b0
+}
+;;
+{ .mfi
+ nop.m 0
+ // absolute value of normalized x
+ fmerge.s fNormX = f1, fNormX
+ nop.i 0
+}
+;;
+{ .mfb
+ nop.m 0
+ // final result for x = 0
+(p13) fma.d.s0 f8 = fPiBy2, f1, f8
+ // exit here if x = 0.0
+(p13) br.ret.spnt b0
+}
+;;
+// if we still here then x is denormal or unnormal
+{ .mfi
+ nop.m 0
+ // set p14 = 1 if normalized x is greater than or
+ // equal to the smallest denormalized value
+ // So, if p14 is set to 1 it means that we deal with
+ // unnormal rather than with "true" denormal
+ fcmp.ge.s1 p14, p0 = fNormX, fDenoBound
+ nop.i 0
+}
+;;
+{ .mfi
+ nop.m 0
+(p14) fcmp.eq.s0 p6, p0 = f8, f0 // Set D flag if x unnormal
+ nop.i 0
+}
+{ .mfb
+ nop.m 0
+ // normalize unnormal input
+(p14) fnorm.s1 f8 = f8
+ // return to the main path
+(p14) br.cond.sptk acos_unnormal_back
+}
+;;
+// if we still here it means that input is "true" denormal
+{ .mfb
+ nop.m 0
+ // final result if x is denormal
+ fms.d.s0 f8 = fPiBy2, f1, f8 // Pi/2 - x
+ // exit here if x is denormal
+ br.ret.sptk b0
+}
+;;
+
+// here if |x| > 1.0
+// error handler should be called
+.align 32
+acos_abs_gt_1:
+{ .mfi
+ alloc r32 = ar.pfs, 0, 3, 4, 0 // get some registers
+ fmerge.s FR_X = f8,f8
+ nop.i 0
+}
+{ .mfb
+ mov GR_Parameter_TAG = 58 // error code
+ frcpa.s0 FR_RESULT, p0 = f0,f0
+ // call error handler routine
+ br.cond.sptk __libm_error_region
+}
+;;
+GLOBAL_LIBM_END(acos)
+
+
+
+LOCAL_LIBM_ENTRY(__libm_error_region)
+.prologue
+{ .mfi
+ add GR_Parameter_Y=-32,sp // Parameter 2 value
+ nop.f 0
+.save ar.pfs,GR_SAVE_PFS
+ mov GR_SAVE_PFS=ar.pfs // Save ar.pfs
+}
+{ .mfi
+.fframe 64
+ add sp=-64,sp // Create new stack
+ nop.f 0
+ mov GR_SAVE_GP=gp // Save gp
+};;
+{ .mmi
+ stfd [GR_Parameter_Y] = FR_Y,16 // STORE Parameter 2 on stack
+ add GR_Parameter_X = 16,sp // Parameter 1 address
+.save b0, GR_SAVE_B0
+ mov GR_SAVE_B0=b0 // Save b0
+};;
+.body
+{ .mib
+ stfd [GR_Parameter_X] = FR_X // STORE Parameter 1 on stack
+ add GR_Parameter_RESULT = 0,GR_Parameter_Y // Parameter 3 address
+ nop.b 0
+}
+{ .mib
+ stfd [GR_Parameter_Y] = FR_RESULT // STORE Parameter 3 on stack
+ add GR_Parameter_Y = -16,GR_Parameter_Y
+ br.call.sptk b0=__libm_error_support# // Call error handling function
+};;
+{ .mmi
+ add GR_Parameter_RESULT = 48,sp
+ nop.m 0
+ nop.i 0
+};;
+{ .mmi
+ ldfd f8 = [GR_Parameter_RESULT] // Get return result off stack
+.restore sp
+ add sp = 64,sp // Restore stack pointer
+ mov b0 = GR_SAVE_B0 // Restore return address
+};;
+{ .mib
+ mov gp = GR_SAVE_GP // Restore gp
+ mov ar.pfs = GR_SAVE_PFS // Restore ar.pfs
+ br.ret.sptk b0 // Return
+};;
+
+LOCAL_LIBM_END(__libm_error_region)
+.type __libm_error_support#,@function
+.global __libm_error_support#